Rheostat.



PATENTED PEB. 13, 1906.

G. E. STEVENS,

RHEOSTAT.

APPLICATION r1LED00T.12,1904.

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MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMYNY, A CQRPORAN 0F NEWT YRK.

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To n// wlw/n. if n 'iflrgl/ concern;

Be it known that I, GEORGE E. STEvnNs,a

' oitizenol the United States, residingat L nn,

county of Essex, State of Massachusetts, iave invented certain new and useful Improvements in ltheostats, .of which the. following is a specification.

The presentinvention relates to rheos'tats; und the principal object of the invention is to provid f a rlieostat which is of iaige capacity relative to its bulk, simple and compact in structure, efficient in operation, and clieapto manufacture.

YThe nature and character of the invention,

together with its various features and advantages, will be best understood upon reference to the followingdescription, taken in connection .with the ace-onipanying; drawings, in

which-l Figure 1 is a, plan view oi' a rheostat construotcd-,in accordance with in)r invention.

l portion of the rotary `member.

liigr. lisjaside elevation 'of the' saine, parts being*l brolwnfaway to' illustrate the ylower Fig. 3 is a. vertical scctiontalieii'on a plane indicated by ftlie line 3 bk''titlig,r tand viewed in the dircction of the arrows, and Fig.` lis a diagram of electric circuits. f v y .'l'iir-arrying out; my invention, although otllier l`orinsof resistances niay be employed,

l. preferably 'en'iplojf ai resistanceuiiit eon struc-ted iii yaccordlinee ywith'the:disclosure in supporting'-blooli's ll and l2, Iii and i4 and -.bolt. andfelanipiiige l ture. 'iliefinsulating intiterial preferably stance ribbon insulated `from ed together bya central vnuts tolorni a'iigid strncconsi i-."olal i-ooi refractory substance titious in haracter, wine-li notonly in ,i tn ii'is, but serves'to bind tliein to liaractmr, which are included between in which tlie'olauiping-bolts l5 andlt extend bolts, press against theI blocks l l, l2, I3, and l-l and l'orce the turns ol tlie winding` together and holtljtlie parts 1n position, 'lheso Specification of LettershPatent. Applicationliled October 12, 1904. Serial No. 228,133,

a unit consists of l rammed Feb. 1s, leus.

ribbon winding and with their respective 65 bolts 15 and 16 and 'are insulated from the supporting-strips 21 b a suitable insulation T he other two Klecks (designated 11 and 14) are composed of some suitable instak loting material, such as soapstone andgeach 7o has set into its upper face a stri oi copjoiefn other conducting material, W "cli .isfjlient 'down between the adjacent ends of the wind ing and the block, thus providing s, contact for the outer end of the bridging contact 2li. gig The contact-strips l25 do not completelyV y cover the upper faces of the blocks 1 and 14j-4 but in each case an insulating-face is left ex# posed, and upon these the outer ends of the ridging contact 26 are adapted-to rest when 8e the rlieostat is in off position. The upper surfaces of the blocks :12 and i3 are also lo#- cated so as to be engaged by the Contact 2n The insulating-block 14 is also rovidod witl1 a binding-post 25, and the adiacenti blocks 85 t2 and 14 are connected by a, strip 27, which constitutes a stop for the rotary Contact 2,6,y

Freni the above it will be seen that esclu oft y the eentral bolts l5 and 16 is in electrical cir. euit with one gend of the resistance-coil go through which it passe-s. Consequently,7 the rlieostat may be. eonneetedup by clamping` the leads between tliclinits 17 or 18 on the one end and between the nuts 19 and 2() on t the other. l furthermore rovido an addio5 tional terminal for each o the insulating-ffbloeksl and I4 by means of an angltrplate 28'; 'lliis plate is inclectrical engagement .with the central bolt in cach instance is lirinly seeured to and insulated from tiidsdroo jacent supporting-strip 21, Suitable olttmpfq t ing-nuts 9 serve to hold the leads n'jplocoi 'llie rotary contactl'o ithe rheostat oon--y sists of a stripof springy conducting materiel wit li its ends split, s oas to provide gentili-iloct-rieal contact with the eiidfblo eks 12 anti 13,4 t be ront act-strips 25, andthe upper surfaceof, the resist ance units 10, with whicliit is adapt ed to engage. The engaging portions ol the units are not covered by an insulating-coating, but are left exposed and may even be smoothed off, so asvto further improve the electrical contact. The center of the contact 26 is apertured so as to fit over the neck 30 of a hollow member 31, rotatably mounted upon the pivot-post 32, located midwa between the resistance unit 10 and exten ing transversely thereto. The pivot-post is secured tothe base 23 through the agency ci a magnet-core 33, which is secured7 to the base by screws 34 and to a projecting lhub on the post by screws 35. A collar 36, retained in position by a set-screw 37, presses down upon upper side of' the contact 26, so asto hold it in position, and a helical s ring 38, coiled about the pivot-post 32 an secured at one end thereto and at the opposite end to the member 31, serves to return the contact to off osition. The magnet-core 33 is provided wit an energizing-coil 39, which is connected by means of suitable terminals 40 between the conductor-blocks 12 and 1.4, This magnet is a retaining or locking magnet andis designed to hold the contact 26 in its on iosition-that is, in that position in which a the resistance of the rheostat is cut out-and prevent it from returning to the 0H position under the action of the returning-spring 38. This action is brought about through the agency of the armature 39a, which is secured to the lower end ,of the rotary member 31, which carries the Contact 26. Normally the resiliency of theeontact 26, bearing at its ends upon the fixedlelement of the rheostat, is sufficient to hold the armature 39 far enough away from the magnet to prevent it from being drawn into engagement therewith. Movement is transmitted to the contact 26 in opposition to the returning-spring 38 by means of an operating-lever 41. This lever has a limited vertical movement between a thrust-bearing 42 at the upper end of the ost 32 and a shoulder 43 on said post, The ever also transmits its motion to the rotary member 31 and thence to the contact 26 by means of a cam projection 44 on the member 31, which engaffes a notch 45 in the adjacent portion of thethandle. of the device the contact 26, which serves as a spring, forces the parts 31 and 41 into engagement with such pressure that the rotation of the lever 41 is transmitted to the member: 3l without the shoulder 46 on the lever riding up over the inclined surface 47 of the cam projection on the member 31. in this way the movement of the operating-lever is transmitted to the contact 26, and it is carried around over the resistance-wimling so as to successively cut out its turns, While the armature remains in the raised position. (Illustrated in Fig, 2.) However, when the Contact 26 has been moved far enough to cut out all the resistance or the rheostat the conthe l In the operation eiatoc tact will be brought up against the stop 27 and its further rotation prevented. A further movement ol' the operating-lever il will cause the shoulder o to ride up on the inclined -surface 47, and thereby force the member 31 and the armature 39 downward against the face of the locking-magnet. ln this position the )ull of the magnet will lie sui'licient to hold tihe parts against return. ln case of failure of current or the occurence ot' other conditions which will sullicientl)v decuergize the magnet the armature will he released, and after being drawn upward bythe spring action of the Contact lo the movable parts will be returned to their oil' position by the return-spring 31.

lt is obvious that resistance units of' other constructions than that herein described may be used and that man)` alterations and modifications in the specific matter illustrated niay he made without departimgT l'rom the spiritand scopo of my invention, l iberol'ore do not wish to he limited to the specific structure shown and described, but aim to cover by the terms of the appended claims all such alterations and modilicarions,

`What i claim as new, and desire ti, secure by Letters latent 'the United Seite. is

1. A rheostat comprising a lined resistance element, a cooperating movable contact a spring for returning the parts to oli' position. a. tiered locking member, a yieldingly-mountml cooperating locking member carried by the movable contact and movable transversely thereto, and means for mechanically moving said locking members inte engagement.

2. A rhecstat comprisi g3; lixed resistance element, a coi'iperating nii-,able mntact, a spring for returning the parts to oil' position, a fixed locldng-magne, an arimitnre therefor cz'trricd by the movable =i^ontact and movable. transversely to thc said contact, a nd means l'or movingsaid armature transversely into operative relation to said magnet.

3. A rhoostat comprisintr a fixed resistance element, a cooperating movable contact, a spring for returning the parts to oil' position, a fixed looking-magnet, a yieldingly-mounted armature therefor carried by the movable contact and movable transversely to the said contact, and means for movingr said armature transversely into operative relation to said magnet.

#1. A. rheostat comprising a hase, a iixed resistance element secured thereto, a cooperating nu fable clement, a spring for returning the parts to oilI position, an elcctromugnet mounted on said base, a violilingly-mounied armature on themm'ahlc elcnmntol' the rhcostat normally held awry-from said magnet, and means for mechanically moving said armature and magnet into operative relation whereby the movable element will be held against vthe tension olm the spring.

.3. ln a rheostat, the combination with a ICO ixed resistance element and a base therefor,

` with said magnet.

6. A rheostat comprising a fixed resistance element, a cooperating movable contact, a xed locking member, a cooperating movable locking member carried b said vmov- ,able contact, an operatingiandle, and

"means whereby the movement of said handle will move said contact toits limiting position and a further movement will bring said locking members into engagement.

7l. A rheostat comprising a fixed resistance element, av coperating movable contact, a fixed locking member, a coperatin movable locking member carried by sai movable contact, an operating-handle, frictional connectin means between said handle and contact wiereby the movement of the former is transmitted to the latter, a stop for limiting the movement of the contact, a cam connection between the lockine'member and the handle whereby u )on a Further movement of the latter the ocking members will be moved imo engagement.

ln a. rbeostat, the combination with a fixed resistance element and a base therefor, of a pivot-post secured to said base, a magnet located at the foot of said post, a rotary armature su )ported on said post and movable longitudinally thereof, an operating-lever mounted on said post above said armature, a yielding laterally-extending,Contact secured to said armature and adapted to enge the fixed element of the rheostat and to d the armature and operating-lever in close engagement, a stop for limiting the movement of said contact, and cooperating cam-surfaces on saidarmature and lever whereby the rotation of said lever is transmitted to said contact to carry it against said stop and its urthermovement forces the armature downward against the magnet.

In witness whereof I have hereunto set my hand this 10th day of October, 1904.

GEORGE E. STEVENS. Witnesses:

'JOHN A, McMANUs, Jr., DUGALD MCK. MCKILLOP. 

